Electromagnetic device

ABSTRACT

An electromagnetic device including a plural number of individual magnetic circuits, each with magnetically operable armatures, assembled in a unit. Each magnetic circuit includes a first coil and two stationary yokes disposed on opposite sides of the coil with an armature extending through the coil and pivoted at one of its ends. (Two armature pivot structures are disclosed.) The other end of the armature is disposed for operating movement between two stationary pole faces, one on each of the two yokes. A second, &#39;&#39;&#39;&#39;extra&#39;&#39;&#39;&#39; coil is disposed around a portion of one of the two yokes for each magnetic circuit. By appropriate energizing of the two coils, selected disposition of the armature can be maintained and attained. The armatures can be used for various purposes, e.g., to operate mechanical devices, or as a relay operator to actuate one or more contact spring sets. The device is assembled in a manner to enable independent operation of the armature of each magnetic circuit without the magnetic circuit affecting the positions of the other armatures in the assembly.

United States Patent Zander et al.

[ 5] Mar. 14, 1972 [54] ELECTROMAGNETIC DEVICE [72] Inventors: Rolf Albin Zander, Storhagsvagen 28A, 125 32, Alvsjo; Per Harry Elias Claesson, Osterhagens Gard 142 00, Trangsund; Sten Daniel Vigren, Mosbacke Torg 16-18, 1 16 20, Stockholm, all of Sweden [221 Filed: July 6,1970

[21 Appl.No.: 52,647

[30] Foreign Application Priority Data July 9, 1969 Sweden ..9718/69 [52] US. Cl ..335/ll2, 335/177 [51] Int. Cl. ..H0ll1 67/14 [58] Field oiSearch ..335/l12, 177,180, 181,182,

Primary ExaminerHarold Broome Attorney-Strauch, Nolan, Neale, Nies & Kurz [5 7] ABSTRACT An electromagnetic device including a plural number of individual magnetic circuits, each with magnetically operable armatures, assembled in a unit. Each magnetic circuit includes a first coil and two stationary yokes disposed on opposite sides of the coil with an armature extending through the coil and pivoted at one of its ends. (Two armature pivot structures are disclosed.) The other end of the armature is disposed for operating movement between two stationary pole faces, one on each of the two yokes. A second, extra coil is disposed around a portion of one of the two yokes for each magnetic circuit. By appropriate energizing of the two coils, selected disposition of the armature can be maintained and attained. The armatures can be used for various purposes, e.g., to operate mechanical devices, or as a relay operator to actuate one or more contact spring sets. The device is assembled in a manner to enable independent operation of the armature of each magnetic circuit without the magnetic circuit affecting the positions of the other armatures in the assembly.

18 Claims, 17 Drawing Figures PATENTEDMARMIQYZ 3.649.938

SHEET 1 [IF 5 109 Ill:

@1134 T nt INVENTORS F495 I ROLF AL N ZANDER BI PER HARRY ELIAS CLAESSON BY STEN DANIEL VIGREN ATTORNEYS ELECTROMAGNETIC DEVICE The present invention relates to an electromagnetic device, comprising a number of magnetic circuits, each circuit comprising a stationary part and a movable armature of magneti cally conducting material; a pivot where a first part of the armature is pivoted to a first portion of the stationary part; a working airgap between a second part of the armature and a second portion of the stationary part; an extra airgap between a third part of said armature and a third portion of said stationary part; said circuit further comprising a first magnetically conducting path adapted to close itself over said working airgap and a second magnetically conducting path adapted to close itself over said extra airgap, both of said magnetically conducting paths passing a common portion of said armature; there being further a working winding which is common for both the magnetically conducting paths and an extra winding which is provided for the second magnetically conducting path.

Such electromagnetic devices are used for several purposes. The movement of the armature when it is actuated may be transmitted by a rib or similar means to a mechanical device to lock said mechanical device in an operative state or in a non operative state. As examples of such use a coin-operated vending machine or a telephone coin box may be mentioned.

Another use for said electromagnetic device is as a relay. In that case the movements of the armature are transmitted by an actuating rib to one or more contact spring sets. Such relays may find a number of applications in for instance telephone equipment.

In modern automatic telephone exchanges there are used so called cross-point switches where contact devices are situated in the cross-points between lines and columns in a coordinate system. For actuation of the contact spring sets in such crosspoint switches an electromagnetic device according to the present invention is especially well suited. A simple solution is to use an electromagnetic device according to the invention for each' contact device e. g., for each cross-point. This is, however, an expensive solution and preferably the electromagnetic device according to the present invention is used in such a way that in a complete cross-point switch with a large number of contact devices there is one armature for each contact device but less windings and stationary structures then the number of armatures. If a cross-point switch has M lines" and N columns an electromagnetic device according to the present invention may be designed as a unitary magnetic structure for each line and one common first winding for each line but a separate second winding for each annature in said line, and as the number of columns has been assumed to be N there are N separate second windings for each line." It has been assumed that there are M lines and thus there will be NxM armatures, M stationary magnetic structures, M first windings and NxM second windings. This is a big saving as compared to the case where separate electromagnetic devices are used. Assuming N columns" and M lines there will be MxN magnetic structures, MxN armatures, MxN first windings and MxN second windings.

According to a further development of the invention it is possible to use for a cross-point switch with M columns" and N lines one single stationary magnetic structure, MxN armatures, N first windings and MN or even M second windings. Therefore, the electromagnetic device according to the invention has a broad-field of application and results in very economic constructions when used in cross-point switches.

When used in cross-point switches the electromagnetic device according to the present invention will lend itself very admirably to be combined with contact devices of different types as multiple fields. Preferably the contact devices include one or more printed circuit boards with cooperating movable and fixed contact springs.

The features which characterize the present invention are stated in the accompanying claims.

For a better understanding of the invention, a detailed description of some preferred embodiments of the same will be given in the following specification which should be read in conjunction with the accompanying drawings:

FIG. 1 is a schematic view of an electromagnetic device according to the present invention and will be referred to when explaining the principle of the invention.

FIG. 2 is a bottom view of a cross-point switch with electromagnetic devices according to the present invention for actuation of contact spring groups.

FIG. 3 is a schematic side elevation of the contact devices in the cross-point switch shown in FIG. 2.

FIG. 4 is a cross section of the cross-point switch shown in FIG. 2 and with two different arrangements of the armatures in the electromagnetic devices.

FIG. 5 is a top view of the cross-point switch shown in FIG. 2 and FIG. 3.

FIG. 5a is a diagrammatical illustration, showing a common winding for each line and a common winding for each column of a cross-point switch.

FIG. 6 is a side view of a multiple field contact set, comprising a printed circuit board for use as electrically conducting connection strips.

FIG. 7 is a top view of the multiple field according to FIG. 6.

FIG. 8 is a top view of a board with a printed circuit arrangement and with contact springs.

FIG. 9 is a side elevation of the board according to FIG. 8.

FIG. 10 is a bottom view of the board shown in FIGS. 8 and FIG. 11 is a plan view of a strip of electrically insulating material supporting a-number of contact springs.

FIG. 12 is a side view of the strip according to FIG. 11.

FIG. 13 is a cross section of the strip according to FIG. 11 and FIG. 12 illustrating how electrically conducting strips are connected to contact springs.

FIG. 14 is further a plan view of a strip of electrically insulating material supporting contact springs.

FIG. 15 is a plan view of a strip of electrically insulating material with contact springs supported by said strip during the mounting of said contact strips;

FIG. 16 is a side view of the strip according to FIG. 15.

FIGS. 2-16 illustrate some embodiments of cross-point switches and multiple field contact sets of such cross-point switches in which the electromagnetic device according to FIG. 1 is used.

In FIG. 1 is shown an electromagnetic device with a stationary structure of magnetic conducting material, for example iron with a low coercive force and a high permeability. The stationary structure comprises a first yoke which may be termed the pulling yoke for reasons which will be evident from the following specification. The first yoke has in the embodim'ent shown a major part 1 parallel to the axis of a winding 9 on a bobbin 8 and situated outside said winding at one side of said axis. Said major part 1 has an extension 2 adjacent to a first end of said winding 9 and this extension 2 is also parallel to the axis of said winding 9 but has been offset in relation to said major part 1 in order to form a pole piece for cooperation with an armature 7 arranged to be movable in an opening in said bobbin 8. The armature 7 is extending substantially in the direction of said axis for the winding 9. At the other end of said major part 1 there is a second extension 3 but this extension is bent at right angle to said major part 1 and is situated outside the end flange of said bobbin 8.

The stationary structure comprises a second yoke which may be termed the selecting yoke for reasons to be given later on. This second yoke has a major part 5 parallel to the axis of said winding 9 and this major part 5 is situated outside said winding at the opposite side of said axis in relation to the major part I. The second yoke has an extension 6 at the said first end of the winding 9 but the extension 6 is bent at right angle to the major part 5 and terminates at a distance from the pole piece 2 so that an airgap 13 is formed between the end of the extension 6 and the pole piece 2. In this airgap 13 the armature 7 is movable between two positions. In a first position the non-actuated or rest position the armature 7 is engaging the extension 6 and in the other position the active position the armature is engaging the pole piece 2. The major part of the second yoke has a second extension 4 at the other end of the winding 9 and this second extension is bent at right angle to the major part 5 and contacts the second extension 3 of the first yoke.

As already stated, the armature 7 extends substantially in the direction of the axis of said winding 9 and is situated in an opening in the bobbin 8 for the winding 9. Said bore opening has such size in relation to the armature that the armature 7 is swingable about a point 12 adjacent to the second end of said bobbin 8 where the extensions 3 and 4 are located. The airgap 13 is naturally wider than the thickness of the armature 7 in order to allow said swinging movement. Preferably, there are nonmagnetic stop pins or equivalent means between the armature and the extension 6 and pole-piece 2 in order to prevent sticking of the armature to the extension 6 or to the pole piece 2, but these stop pins are not illustrated in FIG. 1.

In addition to the winding 9 surrounding the armature 7 there is also a second winding 11 on a bobbin 10 and this second winding surrounds the yoke extension 6.

The electromagnetic device now described operates in the following way. Assume that the armature 7 is resting against the end of the extension 6 and that the winding 11 is energized with a current of a predetermined value in a given sense. It is evident that a magnetic flow will be established in for instance the direction of the arrow 14 in a magnetic circuit including the extension 6, the major part 5 the second extension 4 and the armature 7. There will be a strong magnetic attraction between the armature 7 and the end of the extension 6 and thus the armature 7 will be firmly kept in the position shown in FIG. 1, i.e., in the rest position.

If only the winding 9 is energized, there is a magnetic flux generated through a path comprising the armature 7, the extension 6, the part 5 and the extension 4, as long as the armature remains in the position shown in FIG. 1. It is obvious,

therefore, that with the armature in the rest position either of the windings 9 and 11 may be energized without bringing the armature to leave its rest position shown in FIG. 1.

Now it is assumed that both of the windings 9 and 11 are energized simultaneously with the armature in the rest position shown in FIG. 1. It is further assumed that the current in the winding 11 has such a sense that the magnetic flow in the magnetic part 5 has the direction given by the arrow 14. The current through the winding 9 is assumed to have such a sense that said current when working alone gives a magnetic flow in the armature 7 in the direction given by the arrow 15 opposite to the direction given by the arrow 14. In this case it is evident that the fluxes generated by the windings 11 and 9 may cancel each other in the airgap between the armature and the extension 6 when the current through the winding 9 has a suitable value in relation to the value of the current in the winding 11. In that case, the flow generated by the winding 9 is prevented from flowing through the airgap between the armature and the extension 6. Therefore it flows through the armature 7, the airgap l3 and the pulling yoke 1. As a result the armature will be attracted to the pole piece 2.

If only the winding 9 is energized, there will again be a magnetic flow through the armature 9, the yoke 4, the extension 6 and the airgap between said extension and the armature. Now again, the armature will be firmly retained in its rest position illustrated in the figure, until the winding 1 l is supplied with a current of such value that the magnetic flux through said airgap is cancelled.

lt is thus seen that for a current through only one of the windings 9 or 11 the armature will remain in its rest position but if both said windings are supplied with current at the same time the armature will be moved to its active position and may by this movement operate contact sets when the device is used as a relay or in a selector.

The airgap 13 between the pole piece 2 and the armature 7 is called the working airgap. It is evident from FIG. 1 and from the foregoing description, that there is a first magnetically conducting path which is adapted to close itself over the working airgap, said path comprising the main portion of the armature 7, the pivot between the armature and the extension 3, the pulling yoke l, the pole piece 2 and the working airgap 13. There is also a second magnetically conducting path comprising the main portion of the armature 7, the pivot, the contact surface between the extension 3 and the extension 4, the selecting yoke 5, the extension 6 and the airgap between the extension 6 and the armature 7. Said airgap is called the extra airgap. It is apparent from FIG. 1 that the winding 9, which is called the working winding surrounds the portion of the armature 7 which is common for both of said magnetically conducting paths and that the winding 11 which is called the extra winding surrounds a portion of the stationary structure which is comprised in the second magnetically conducting path.

When the current through the windings 9 and 11 is broken the armature will return to the rest position by a spring used to hold the armature in the rest position.

In the introductory part of the specification it has been stated that an electromagnetic device according to the invention has many uses. It is evident that in such cases where there is a need for an actuation when two currents are occurring simultaneously but with assurance that no actuation is to take place when only one current is present the electromagnetic device according to the invention may be successfully used. Already coinoperated vending machines and telephone coin boxes have been given as examples especially in such cases where several species of coin are to be used. Many other applications are evident to anyone skilled in the art.

Further an electromagnetic device according to the present invention may be used together with one or several relay contact sets, and by the said expedient there results an electromagnetic relay which will operate for two predetennined currents when these currents are applied simultaneously but will not operate when only one current is present. Such a relay will have applications in telephone exchange equipment. A very important application of this kind is for cross-point switches.

In modern telephone equipment cross-point switches are used as selectors in order to establish a connection between two different circuits among a number of circuits which are connected to the lines" and columns in such a cross-point switch. It is always a connection between a line and a column that is to be established. In order to bring about such a connection the cross-point switch will have all the relays in the line in question energized by a predetermined current and all the relays in the columns in question will also be energized by a predetermined current. When relays using the electromagnetic device according to the present invention are utilized as cross-point relays it is thus evident that of all the relays in said line and said column, it is only the relay at the cross-point between the line and the column that will operate. All the other relays in said line and said column are energized by only one current and will be inactive. It has turned out that relays using the electromagnetic device according to the present invention will function in a very satisfactory way when used in cross-point switches as the relays which receive only one current will with certainty be held in their rest positions, even if the single energizing current varies within wide limits.

The simplest way to construct a cross-point switch from relays using the present invention is to put into the cross-point switch as many such relays as the product of the number of lines and columns. If there are M lines and N columns there will be used a total of MXN such relays in the cross-point switch in question.

However, a reduction of parts may be attained by using multiple relays with for instance only one stationary magnetic structure for each line and one first winding for said structure, surrounding all the armatures, and one separate second winding for each relay. One way of constructing such a multiple as that part A of FIGS. 4 and 5 that is situated to the right of 5 the dash-dotted line. In FIG. 4 is to be seen that counterparts to the selecting yoke 5 which here is a magnetic plate 211, the extension 6 as the detail 230, the winding 11 as detail 232, the armature 7 as detail 113, the winding 9 as detail 113a and the extension and pole piece 2 as detail 110cd as part of a magnetic plate 110. At the left end of FIG. 5 is also shown the contact springs 107 which are stationary contact springs for each relay in the line (three relays in a line for three columns).

The magnetic plate 110 is called the first magnetic plate and the magnetic plate 211 is called the second magnetic plate. In the embodiment illustrated said plates are common for all relays in the whole selector.

When a unit like the part A to the right at FIGS. 4 and 5 is used for a line, there will be a magnetic connection between the magnetic plate 211 and the magnetic plate 110. This magnetic connection may be a magnetic strip joining the magnetic plates 211 and 110 and situated normally to these plates at least at one of their edges but preferably at two or more edges of said plates, and also to the drawing plane. For reasons of clarity those strips are not shown on the drawings. A number of such multiple relays as represented by the unit A of FIG. 5 are located vertically above each other or beside each other with the springs l07b connected to form a multiple field for the columns and with the springs 108 connected to form a multiple field for the lines. In the construction now described there is a separate winding 232 for each separate relay inthe multiple relay for one line but the winding 113a may be common for all the separate relays used for a line and thus surround all the arrnatures in said relays. In FIG. 5 said winding 113a extends from the top portion of the section A to its bottom portion. If this teaching is applied to FIG. 1 the winding 9 should be extended that much normally to the drawing plane that is needed to surround all the armatures 7, which are situated above each other in a direction normal to the drawing plane.

However, in many cases, it is preferable to use the construction shown in FIG. 4 and FIG. 5 for a cross-point switch. Though the unit illustrated in FIGS. 4 and 5 has only three lines and three columns, it is apparent that it can be made for any number of lines and columns that is practical and desired. In this case all the relays are arranged so that all the armatures will be situated substantially in one and the same plane. In FIG. 4 there are shown armatures of slightly different configuration, with the two armatures of a first configuration being situated to the left of the dashed line and an armature of a second configuration being situated to the right of the said dashed line and thus at the section A. In most other respects the relays with the different armatures are quite alike.

In FIG. 4 is shown a first plate 110 and this plate consists of magnetic conducting material iron with a low coercive force and high permeability and in this plate 110 there are a number of apertures for the windings 111a, 112a and 113a, and as each of the windings 111a, 112a, 113a will surround all the three armatures for a line these apertures will have a corresponding width but will leave lands at the upper and lower edge of said plate 110 as seen in FIG. 5. Between these apertures there will remain intermediate strips 110ab, 110bc and an end strip 1l0cd of said plate 110. These strips l10ab, 110bc and 110cd will each constitute a multiple pole piece 2 for the armatures for each line. This multiple pole piece l10ab, l10bc or 110cd will cooperate with a major part 1 which consists of said lands at the upper and lower edges of the plate 110 outside the apertures for the windings 111a etc. plus part of a second plate 211 of magnetic conducting material, located substantially in parallel to the plate 110 and situated above the lastnamed plate (as seen in FIG. 4). The plate 211 comprises the details 4, 5 and 6 in the construction shown in FIGS. 1, 4 and 5 with the details 210, 220 and 230 corresponding to detail 6. The windings 11 and the bobbins 10 are also shown in FIG. 4 as the details 212, 222 and 232 for the windings. The bobbins have no reference numerals in FIG. 4. Said bobbins form parts of a plate 200 of insulating material. Said second plate 211 is preferably bent down at the horizontal edges, as seen in FIG. 5, to make magnetic contact to the edges of said first plate 110. Also the plate 211 has apertures (as is clearly seen in FIG. 5) surrounding the individual parts 210, 220 and 230, which are bent down to cooperate with the individual armatures.

In FIG. 4 to the left, there are two armatures 111 and 112 illustrated, which together with the other armatures for each line, are located in the windings 111a and 1121: respectively on the bobbins 111b and 112b respectively. Each of said armatures 111 and 112 is substantially of Z-configuration and the left part of each armature has a bearing constituted by two surfaces at right angle to each other and engaging the lower edge of the aperture in the plate or the strip 1l0ab (which also is serving as a pole piece for the armature 111 while the pole piece for the armature 112 is constituted by the strip 1 10bc).

In the rest position shown in FIG. 4, the armature 111 is with its right end engaging the part 210 and at this end of the armature there are means, pole pins or equivalent means, to prevent sticking as far as the part 210 and the strip 1100b are concerned. In order to hold the armatures 111 and 112 respectively in the rest positions, there are biasing springs 111:: and 112c respectively and these springs have one end fixed tothe armature adjacent the bearing and the other end of the spring engaging a part of the coil bobbin 1 1 lb and 112b respectively in the opening of such bobbin. From FIG. 4 it is also evident that the free end of said spring 1110, 1120 is situated opposite the wall in the aperture in the plate 110 and thus will prevent the armature to be withdrawn.

As already stated, the right end of each armature is situated above the detail 1l0ab and 110bc respectively, said details are pole pieces for the respective armatures 111 and 112, but in the rest positions the armature is spaced from its pole piece by a working airgap 111, 112'. Each armature has also an actuating rib llle and 112e respectively. This actuating rib actuates a movable contact spring 107 for moving said spring to engage a stationary contact spring 108. In FIGS. 2 and 4, these contact springs 107 and 108 are shown and it is apparent that the movable contact springs 107 are constituted by a continuous strip with bends 107a between each line section of a crosspoint switch. Thus, the movable contact springs for a column are connected to each other. The stationary contact springs 108 are individual for each relay in each line but are connected together for each line and brought out to terminals 1080 by connections 108a and 108a. In the same way, the movable contact springs 107 for each column are brought out to individual terminals 107b.

The bends 107a serve to give the different sections of each continuous strip forming the movable contact springs 107 a sufficient flexibility, so that the section to the left of a bend 107a as seen in FIG. 4 may be flexed sufficiently, to make contact with the adjacent fixed contact spring 108. The part of each spring 107 located to the right of each bend is fixed in the block 109. There are such blocks 109 for each column and each such block 109 is common for all the lines crossing said column. v

To the right in FIG. 4 is shown another type of armature 113. This armature is substantially straight and its left end is resting on the top of the strip 110bc and is prevented to be displaced to the left from its predetermined position by an enlarged flange 113b of the bobbin 113b. The flange 1l3b' has such a shape, with the flange not resting on the strip l10bc that the armature 113 will be held against the strip 110bc. Preferably, there is a thin sheet of non magnetic material on the upper surface of the strip l10bc in order to prevent sticking of as well the left end of the armature 113 as the right end of the armature 112. Measures are also taken to prevent sticking of the armature 113 to the part 230 and to the strip 110011. As in the other cases there is a working airgap 113' between the armature 113, when in rest position, and the strip 110cd. Also in this case, there is a spring 1130 for holding the armature 113 in the shown rest position when none of the windings 232 and 113a is energized.

In connection with FIG. 4 and FIG. 5 has been described and shown a cross-point switch where there are individual extra windings such as 212, 222 and 232 for each part 210, 220 and 230. Therefore in the illustrated embodiment, there are 3X3 extra windings or 9 windings. In the same way as has been stated for the windings 111a, 112a and 113a, where one winding is common for all the armatures for a line, it is possible to form one extra winding which is common for all the parts 210, 220 and 230 belonging to a column. In the case shown in FIG. 4, there would be needed three holding windings instead of the nine holding windings that are shown.

In FIG. 5a is in a schematic way shown an arrangement of windings for a cross-point switch with three lines and three columns, with the lines designated L1, L2 and L3 and with the columns designated C1, C2 and C3.

The armatures have been shown as rectangles and are designated all, 012, al3 for the first line, a2l, a22, a23 for the second line and a31, a32, a33 for the third line. It appears from the figure that the armatures for the first column are denoted all, 2121, a31, for the second column a12, a22, a32 and for the third column a13, a23, a33.

For each armature there has been very schematically shown a contact set illustrated as a simplified make contact. The windings have been shown as single turns and it is clearly shown that there is a first winding for the line L1, a second winding for the line L2 and a third winding for the line L3. Each of the said windings encompasses the three arrnatures for the line in question (one armature for each column). In the same way, there is a first winding for the first column C1, a second winding for the second column C2 and a third winding for the third column C3.

It is evident that each armature is encompassed by two windings, viz one line winding and one column winding. If the armature a23 is taken as an example it is clear that the said armature a23 is encompassed by the winding serving the line L2 and is further encompassed by the winding serving column C3. If the windings for line L2 and for column C3 both are energized it is evident that the armature a23 will be influenced by two energized windings and therefore will be actuated. None of the other armatures will be influenced by more than one energized winding and therefore all of them will remain in their rest positions.

For the sake of simplicity, in FIG. 5a both the line windings and the column windings are shown to surround the armatures. When the circuit of FIG. 5a is applied to a magnetic device illustrated in, for example, FIG. 1, each line winding corresponds to a number of windings 9, surrounding a number of armatures and each column winding corresponds to the number of windings 11 which do not surround any armature but a number of extensions 6.

The same general arrangement may naturally be used for a matrix with M lines and N columns and it is easy to find out that in such a case there will be needed totally M+N windings. This is to be compared to the fact that if for each cross-point a separate relay is used and this relay has one line"-winding and one column-winding the total number of windings will be MXN windings. For a l0 l0 matrix there will in one case be needed 100 windings but in the other case only windings.

To anyone skilled in the art it is evident that there are many possibilities to form a cross-point switch where the magnetic structure and the windings have shapes differing from the shown. All such modifications will fall within the scope of the claims as long as the principle for the electromagnetic device according to the present invention is adhered to.

Instead of the contact sets for the cross-point switch shown in FIGS. 2-5 inclusive, where the movable and stationary contact springs and the connections consist of metal strips, it is also .possible to use contact sets where movable springs and stationary springs are positioned on a board with connections formed as a printed circuit. Such a contact set array will be described in connection with the FIGS. 6 to 16 inclusive.

In FIGS. 6 to 9, there is shown a side elevation of a multiple field contact set suitable for use in a cross-point switch with electromagnetic devices according to the present invention. The multiple field comprises a board 601 of electrically insulating material and on the side 601a of said board there is formed a conducting arrangement in the form of a printed circuit comprising parallel electrically conducting strips 610 615 (FIG. 7). It is to be observed that here has been shown, as an example, only a multiple field with 3 X 6 cross-points. In the multiple contact springs 620- 625, 620a- 625a, 630a- 635a etc. (in FIGS. 6 8) positioned one after another in the longitudinal direction of each strip 610 to 615, respectively. The left hand end of each spring (FIG. 8) is fastened to the underlying strip by means of two pins 801, 802 which pass through holes in the board 601 and are bent at the opposite side of said board. In addition to or instead of said fastening means, each spring 620, 620a and so on, may be welded or soldered to the underlying strip. The contact springs 620- 625, 620a- 625a have contact surfaces 620'-625', 620a'625a situated adjacent to further contact springs 630- 635, 630a- 635a. The lastnamed contact springs 630- 635, 630a- 635a have also contact surfaces 630a'635a, 630b'635b for cooperation with said contact areas 620625' etc. on the contact springs 620 625 etc. The right hand end of each spring 620- 620a is capable of being flexed from the board 601 and being brought to engagement with the adjacent spring 630, 630a and so on. Thus the springs 620, 620a etc. are the movable contact springs and the springs 630, 630a etc. are the fixed contact springs in the contact set. If electrically insulating material is placed between the contact springs 620-625, 620a-625a etc. and the underlying contact strips 610 to 615 the contact areas on said contact springs may be adapted to cooperate with the strips and then each strip should have a corresponding contact area. In the embodiment shown, however, the contact springs 620-625 etc. are arranged-as shown in FIG. 6.

The board has a number of apertures 6l0615 (see FIG. 7) situated near the contact areas of the contact springs 620-625, 620a-625a. Through said apertures the ribs or rods or similar means for actuating said contact springs are passing. Said rib or rod is connected to or forms a part of an actuating rib llle, l l2e etc. in the corresponding electromagnetic relay in the cross-point switch shown in FIGS. 2-5. The fixed or stationary contact springs 630, 630a etc. may preferably be made of thin material and have such a bias that their respective free ends, for example the free end of the contact spring 635, is pressed against an adjacent support of electrically insulating material. Said support may be a part of an insulating strip 603, 604 (FIG. 6) by means of which the fixed contact springs 635, 635a etc. are fastened to the board 601. In FIG. 6, the spring 635, for example, may be extended a little to the right and the extension might be adapted to press against the insulating strip 603 to which the springs 635a etc. are fastened. Said springs 635a etc. should be a little shorter at their left ends so that there would be no contact between each of the springs 635 etc. and the springs 635a etc.

From FIG. 7, it is evident that each of the strips 603, 604

etc. is supporting a plurality of stationary springs, located side by side.

The pins or lugs 801, 802 (FIGS. 8 to 10) which keep each movable contact spring fixed to the board 60l are connected by soldering or the like to metallic strips located on the opposite side of the board.

Said metallic strips form parts of another printed circuit illustrated in FIG. 10. Said printed circuit comprises a number of such metallic strips equal to the number of movable contact springs'Each strip 710 has the shape of an L with one leg 710a parallel to the contact spring 620a and with the other leg 710b at right angle to said first leg 710a and extending to the edge 601' on said board 601 for use as a terminal at said edge.

As already described, the strip 603 supports the fixed con tact springs 630a-635a arranged alongside each other. In said strip 603 there are striplike connection elements as parts of a printed circuit arrangement and these electrically conducting strips are situated in grooves (see FIG. 13) in said insulating strip 603. In FIG. 11 there are shown two such electrically conducting strips with every other contact spring 630a, 632a, 634a connected tothe first strip'30l and the remaining contact springs 631a, 633a, 635a connected to the second strip 302. At the point 303 said conducting strip 301 goes down in an aperture in said strip 603 so that electric contact between said electrically conducting strip 301 and a contact spring 634a on the opposite side of said electrically insulating strip 603 may be obtained by soldering, welding or the like. In a similar way there are apertures at the points 304 and 305 to bring about electric contact between said electrically conducting strip 301 and the contact springs 632a and 630a. If there are three electrically conducting strips on an electrically insulating strip 603 each of said electrically conducting strips will in a corresponding way be electrically connected to every third contact spring. A similar relationship will exist for other numbers of electrically conducting strips.

In FIG. 11 is also shown that the contact springs 630a-635a have contact areas 630a'-635a and that the front or free ends of said contact springs are mechanically interconnected by means of an integral common tongue 330 (shown hatched). By this measure the manufacturing of contact springs in a large scale will be simplified. In FIG. 12 is shown that the electrically conducting strips 301 and 302 have connecting tags 331' and 332 (see also FIG. 8) for cooperation with electrically conducting strips 760 and 761 on the other side 60lb of the board 601 (see FIG. and said lastnamed strips 760 and 761 are extending to the edge 601' of the board 601 to be used as terminals. Said lastnamed terminals are arranged adjacent to the terminals on the other side 601a of the board 601.

In FIG. 14, the contact springs 630a-635a are shown attached to said insulating strip 603 at only one side of said strip and it is evident that said strip 603 may have grooves for said contact springs. It is also possible to form said strip 603 as a small board with a printed circuit. The contact springs 630a-635a should in such a case have tags or pins for the connection to an electrically conducting strip in said printed circuit. Each contact spring that is to be connected to one and the same electrically conducting strip will have the tags or pins formed at the same position on the individual contact springs.

In FIGS. 15- and 16 is shown an alternative embodiment where the contact springs 630a635a are supported on said insulating strip 603 in such a way that each contact spring is integral with a tongue 330 at one end and is integral with a second tongue 330' at its other end (said tongues 330 and 330 shown hatched). Said tongues 330 and 330 are to be removed in order to get a functionable multiple field and are used only as an aid when the contact springs are manufactured and mounted on said strip 603. That part of each contact spring that has been referenced as 630a" 635a" has soldering apertures or holes for individual circuit connection of said contact springs.

To anyone skilled in the art it is evident that there are many modifications possible using the same general principles as have been stated for the shown multiple field and as an example it may be said that there may be conducting strips as part of printed circuits on one or both sides of the board for connection to the movable and stationary contact springs.

The now described multiple field may be manufactured in the following way. The starting point is a board of electrically insulating material and this board is provided with a printed circuit constituting the electrically conducting strips 610-615. Thereafter a number of contact spring sets are to be positioned in predetermined positions on said board. Each contact spring in a set is manufactured as already described in connection with FIGS. 15 and 16 with the ends of the contact springs joined by tongues so that the contact springs during the manufacture and mounting are being held in a predetermined positional relationship to each other. When the contact springs have been attached to an electrically insulating strip said joining tongues are removed so that the contact springs are not longer mechanically and electrically interconnected by said tongues. This removal may be done by using a suitable tool such as a cutter or the like.

In the board there may be grooves for the electrically conducting strips 610-615 and there may be punched holes or apertures for connection tags or pins for electrical interconnection of conduction strips and/or contact springs on opposite sides of the board.

The shown and described embodiments of the electromagnetic device and cross-point switches with such electromagnetic devices as actuating devices for sets of contact springs and multiple fields are only examples and modifications and variations may be made within the scope of the invention as stated by the claims.

What we claim is:

1. In an electromagnetic device with a group of relays, for example in a coordinate selector where the relays are arranged in lines and columns crossing each other, each relay including a magnetic circuit, each magnetic circuit comprising a stationary part and a movable armature of magnetically conducting material, a pivot where a first part of said armature is pivoted to a first portion of the stationary part, a working airgap between a second part of the armature and a second portion of the stationary part, at least one extra airgap between a third part of the armature and a third portion of said stationary part; each said circuit further comprising a first magnetically conducting path adapted to close itself over said working airgap and a second magnetically conducting path adapted to close itself over-said extra airgap, both of said magnetically conducting paths passing a common portion of said armature, there being further a working winding which is common for both of said magnetically conducting paths and an extra winding which is provided for the second magnetically conducting path, and wherein said working winding surrounds said common portion of the armature and said extra winding surrounds a portion of said stationary part which is included solely in said second magnetically conducting path; a first plate of magnetizable material comprises said second portion of the stationary part for the magnetic circuits of a plurality of the relays; a second plate comprises said third portion of the stationary part of the same magnetic circuits forsaid plurality of relays; said plates each having a portion which is substantially parallel to a corresponding portion of the other plate; said two plates being in magnetical connection with each other along at .least one of their edges; and wherein for each magnetic circuit, the third portion of the stationary part comprises a pin protruding from the second plate and directed to the first plate, said pin being integral with said second plate and said extra winding surrounding said pin.

2. In an electromagnetic device with a group of relays, for example in a coordinate selector where the relays are arranged in lines and columns crossing each other, each relay including a magnetic circuit, each magnetic circuit comprising a stationary part and a movable armature of magnetically conducting material, a pivot where a first part of said armature is pivoted to a first portion of the stationary part, a working airgap between a second part of the armature and a second portion of the stationary part, at least one extra airgap between a third part of the armature and a third portion of said stationary part; each said circuit further comprising a first magnetically conducting path adapted to close itself over said working airgap and a second magnetically conducting path adapted to close itself over said extra airgap, both of said magnetically conducting paths passing a common portion of said armature, there being f$rther a workingwinding which is common for both of said magnetically conducting paths and an extra winding which is provided for the second magnetically conducting path, and wherein said working winding surrounds said common portion of the armature and said extra winding surrounds a portion of said stationary part which is included solely in said second magnetically conducting path; a first plate of magnetizable material comprises said second portion of the stationary part for the magnetic circuits of a plurality of the relays; a second plate comprises said third portion of the stationary part of the same magnetic circuits for said plurality of relays; said plates each having a portion which is substantially parallel to a corresponding portion of the other plate; said two plates being in magnetical connection with each other along at least one of their edges; and wherein for each magnetic circuit, the armature is constituted by an elongated rod, the one end of which constitutes said first part of the armature, which is pivoted to a point at or near to that part of said first plate which forms the pivoting place of said stationary part, said armature extending ih parallel to said two plates, said working airgap being provided between one side of the opposite end of said armature and a part of said first plate, and said extra airgap being provided between the other side of said opposite end of the armature and the end of the pin which belongs to the magnetic circuit and which is integral with said second plate.

3. A device according to any of the claims 2, forming a coordinate selector, in which said two plates are common for a plurality of magnetic circuits, located after each other and beside each other in lines and columns in a coordinate pattern, wherein one or more further plates of insulating material are located in parallel to the first and second plates, said further plate or plates being provided with a printed circuit pattern which forms connection conductors for a contact multiple field belonging to the selector and further fastening points for movable contacts comprised in said multiple field and also fixed contacts fastening points for such contacts, said movable contacts being actuated by ribs which are in mechanical engagement with the armatures in the magnetic circuits.

4. A device according to claim 3, wherein movable contact springs (620 62S, 620a 6250 etc.) are fastened after each other and parallel to each other on strips (610 615) comprised in said printed circuit said movable contact springs being defiectable with one end of each spring for making contact with fixed contact springs (635, 635a, 635b etc.) located adjacent to said printed circuit or to a printed circuit which is located in parallel to the first mentioned printed circuit.

5. A device according to claim 4, wherein one end of each of said contact springs is fastened to an insulating strip (603, 604) and the other end is biased towards the movable contact springs of said printed circuit, said biased ends of the fixed contact springs being supported by a. free part of one of said insulating strips (603,604) which serves as a fastening means for fixed contact springs belonging to the next row or column.

6. A device according to claim 3, wherein each movable contact spring is provided with a number of lugs (801, 802), said lugs penetrating holes in said printed circuit board and cooperating with electric conducting layers (710 a) located on the other side of said printed circuit board.

7. A device according to claim 6, wherein said additional conducting layer (710a) for one contact spring has the shape of an L" the one part of which extends in parallel to the contact spring and the other part of which extends at a right angle to said contact spring, said last mentioned part extending all the way to the edge of the card where it forms a contact surface for the contact spring.

8. A device according to claim 3, wherein the printed circuit board is provided with a number of openings (610' 615') located adjacent to the contact surfaces of the movable con tact springs, and in which pins or ribs or other actuating mem- 10. In an electromagnetic device with a group of relays, for example in a coordinate selector where the relays are arranged in lines and columns crossing each other, each relay in cluding a magnetic circuit, each magnetic circuit comprising a stationary part and a movable armature of magnetically conducting material, a pivot where a first part of said armature is pivoted to a first portion of the stationary part; a working airgap between a second part of the armature and a second portion of the stationary part, at least one extra airgap between a third part of the armature and a third portion of said stationary part; each said circuit further comprising a first magnetically conducting path adapted to close itself over said working airgap and a second magnetically conducting path adapted to close itself over said extra airgap, both of said magnetically conducting paths passing a common portion of said armature, there being further a working winding which is common for both of said magnetically conducting paths and an extra winding which is provided for the second magnetically conducting path, and wherein said working winding surrounds said common portion of the armature and said extra winding surrounds a portion of said stationary partwhich is included solely in said second magnetically conducting path; a first plate of magnetizable material comprises said second portion of the stationary part for the magnetic circuits of a plurality of the relays; a second plate comprises said third portion of the stationary part of the same magnetic circuits for said plurality of relays; said plates each having a portion which is substantially parallel to a corresponding portion of the other plate; said two plates being in magnetical connection with each other along at least one of their edges; and wherein for each magnetic circuit said armature and the working winding is provided in an opening in said first plate, the armature being pivoted near to one of the boundary borders of said opening and the working airgap being provided near to the opposite boundary border of said opening.

11. A device according to claim 10, wherein for the armatures of a plurality of the magnetic circuits which are located ,ing in said first plate by means of lugs provided on said bobbin, said lugs having for example barb-like projections which grasp the edges of the opening and wherein said armature is kept in the opening of the bobbin by means of a leaf spring which also serves to keep the non-pivoted end of the armature against the end of the associated pin (210,220,230) when the armature is in its non actuated position.

13. In an electromagnetic device with a group of relays, for example in a coordinate selector where the relays are arranged in lines and columns crossing each other, each relay including a magnetic circuit, each magnetic circuit comprising a stationary part and a movable armature of magnetically conducting material, a pivot where a first part of said armature is pivoted to a first portion of the stationery part, a working airgap between a second part of the annature and a second portion of the stationary part, at least one extra airgap between a third part of the armature and a third portion of said stationary part; each said circuit further comprising a first magnetically conducting path adapted to close itself over said working airgap and a second magnetically conducting path adapted to close itself over said extra airgap, both of said magnetically conducting paths passing a common portion of said armature, there being further a working winding which is common for both of said magnetically conducting paths and an extra winding which is provided for the second magnetically conducting path, and wherein said working winding surrounds said common portion of the armature and said extra winding surrounds a portion of said stationary part which is included solely in said second magnetically conducting path; a first plate of magnetizable material comprises said second portion of the stationary part for the magnetic circuits of a plurality of the relays; a second plate comprises said third portion of the stationary part of the same magnetic circuits for said plurality of relays; said plates each having a portion which is substantially parallel to a corresponding portion of the other plate; said two plates being in magne,ical connection which each other along at least one of their edges; and wherein each plate has the shape of an elongated rib, which is common for a plurality of armatures arranged side by side, which annatures are surrounded by a coil which may be common for all the armatures, and that a surface is provided at one edge of said plates which surface forms a pole piece for the working airgaps for all the armatures and that said second plate has pins directed against the armatures and extending from the edge of the other plate,

said pins forming pole pieces in the extra airgap, said plates being magnetically connected to each other along the edges which are opposite to the edges provided with pole pieces.

14. A device according to claim 13, wherein a plurality of units comprising said two plates with associated armatures and windings are assembled together in parallel to each other to -form a coordinate selector.

15. In an electromagnetic device, a number of magnetic circuits, each circuit comprising a stationary part and a movable armature of magnetically conducting material, a pivot where a first part of said armature is pivoted to a first portion of the stationary part, a working airgap between a second part of the armature and a second portion of the stationary part, at least one extra airgap between a third part of the armature and a third portion of said stationary part; each said circuit further comprising a first magnetically conducting path adapted to close itself over said working airgap and a second magnetically conducting path adapted to close itself over said extra airgap, both of said magnetically conducting paths passing a common portion of said armature, there being further a working winding which is common for both of said magnetically conducting paths and an extra winding which is provided for the second magnetically conducting path, and wherein said working winding surrounds said common portion of the armature and said extra winding surrounds a portionof said stationary part which is included solely in said second magnetically conducting path, means for supplying magnetizing current to said working winding, and means for supply magnetizing current to said extra winding 16. A device according to claim 15 in which each magnetic circuit is comprised in a relay of a group of relays, for example in a coordinate selector, where the relays are arranged in lines and columns crossing each other, wherein a first plate (110) of magentizable material comprises said second portion of the stationary part for the magnetic circuits of a plurality of the relays, and a second plate (211) comprises said third portion of the stationary part of the same magnetic circuits, said plates having each a portion which is substantially parallel to a corresponding portion of the other plate, said two plates being in magnetical connection with each other along at least one of their edges.

17. In an electromagnetic device, a number of magnetic circuits, each circuit comprising a stationary part and a movable armature of magnetically conducting material, a pivot where a first part of said armature is pivoted to a first portion of the stationary part, a working airgap betweena second part of the armature and a second portion of the stationary part, at least one extra airgap between a third part of the armature and a third portion of said stationary part; each said circuit further comprising a first magnetically conducting path adapted to close itself over said working airgap and a second magnetically conducting path adapted to close itself over said extra airgap, both of said magnetically conducting paths passing a common portion of said armature, there being further a working winding which is common for both of said magnetically conducting paths and an extra winding which is provided for the second magnetically conducting path, and wherein said working winding surrounds said common portion of the'arrnature and said extra winding surrounds a portion of said stationary part which is included solely in said second magnetically conducting path, said extra winding being located adjacent to said extra airgap.

18. In an electromagnetic device, a number of magnetic circuits, each circuit comprising a stationary part and a movable armature of magnetically conducting material, a pivot where a first part of said annature is pivoted to a first portion of the stationary part, a working airgap between a second part of the armature and a second portion of the stationary part, at least one extra airgap between a third part of the annature and a third portion of said stationary part; each said circuit further comprising a first magnetically conducting path adapted to close itself over said working airgap and a second magnetically conducting path adapted to close itself over said extra airgap, both of said magnetically conducting paths passing a common portion of said armature, there being further a working winding which is common for both of said magnetically conducting paths and an extra winding which is provided for the second magnetically conducting path, and wherein said working winding surrounds said common portion of the armature and said extra winding surrounds a portion of said stationary part which is included solely in said second magnetically conducting path, said extra winding being located adjacent to said extra airgap, means for supplying magnetizing current to said working winding, and means for supplying magnetizing current to said extra winding. I 

1. In an electromagnetic device with a group of relays, for example in a coordinate selector where the relays are arranged in lines and columns crossing each other, each relay including a magnetic circuit, each magnetic circuit comprising a stationary part and a movable armature of magnetically conducting material, a pivot where a first part of said armature is pivoted to a first portion of the stationary part, a working airgap between a second part of the armature and a second portion of the stationary part, at least one extra airgap between a third part of the armature and a third portion of said stationary part; each said circuit further comprising a first magnetically conducting path adapted to close itself over said working airgap and a second magnetically conducting path adapted to close itself over said extra airgap, both of said magnetically conducting paths passing a common portion of said armature, there being further a working winding which is common for both of said magnetically conducting paths and an extra winding which is provided for the second magnetically conducting path, and wherein said working winding surrounds said common portion of the armature and said extra winding surrounds a portion of said stationary part which is included solely in said second magnetically conducting path; a first plate of magnetizable material comprises said second portion of the stationary part for the magnetic circuits of a plurality of the relays; a second plate comprises said third portion of the stationary part of the same magnetic circuits for said plurality of relays; said plates each having a portion which is substantially parallel to a corresponding portion of the other plate; said two plates being in magnetical connection with each other along at least one of their edges; and wherein for each magnetic circuit, the third portion of the stationary part comprises a pin protruding from the second plate and directed to the first plate, said pin being integral with said second plate and said extra winding surrounding said pin.
 2. In an electromagnetic device with a group of relays, for example in a coordinate selector where the relays are arranged in lines and columns crossing each other, each relay including a magnetic circuit, each magnetic circuit comprising a stationary part and a movable armature of magnetically conducting material, a pivot where a first part of said armature is pivoted to a first portion of the stationary part, a working airgap between a second part of the armature and a second portion of the stationary part, at least one extra airgap between a third part of the armature and a third portion of said stationary part; each said circuit further comprising a first magnetically conducting path adapted to close itself over said working airgap and a second magnetically conducting path adapted to close itself over said extra airgap, both of said magnetically conducting paths passing a common portion of said armature, there being further a working winding which is common for both of said magnetically conducting paths and an extra winding which is provided for the second magnetically conducting path, and wherein said working winding surrounds said common portion of the armature and said extra winding surrounds a portion of said stationary part which is included solely in said second magnetically conducting path; a first plate of magnetizable material comprises said second portion of the stationary part for the magnetic circuits of a plurality of the relays; a second plate comprises said third portion of the stationary part of the same magnetic circuits for said plurality of relays; said plates each having a portion which is substantially parallel to a corresponding portion of the other plate; said two plates being in magnetical connection with each other along at least one of their edges; and wherein for each magnetic circuit, the armature is constituted by an elongated rod, the one end of which constitutes said first part of the armature, which is pivoted to a point at or near to that part of said first plate which forms the pivoting place of said stationary part, said armature extending in parallel to said two plates, said working airgap being provided between one side of the opposite end of said armature and a part of said first plate, and said extra airgap being provided between the other side of said opposite end of the armature and the end of the pin which belongs to the magnetic circuit and which is integral with said second plate.
 3. A device according to any of the claims 2, forming a coordinate selector, in which said two plates are common for a plurality of magnetic circuits, located after each other and beside each other in lines and columns in a coordinate pattern, wherein one or more further plates of insulating material are located in parallel to the first and second plates, said further plate or plates being provided with a printed circuit pattern which forms connection conductors for a contact multiple field belonging to the selector and further fastening points for movable contacts comprised in said multiple field and also fixed contacts fastening points for such contacts, said movable contacts being actuated by ribs which are in mechanical engagement with the armatures in the magnetic circuits.
 4. A device according to claim 3, wherein movable contact springs (620 - 625, 620a - 625a etc.) are fastened after each other and parallel to each other on strips (610 - 615) comprised in said printed circuit said movable contact springs beinG deflectable with one end of each spring for making contact with fixed contact springs (635, 635a, 635b etc.) located adjacent to said printed circuit or to a printed circuit which is located in parallel to the first mentioned printed circuit.
 5. A device according to claim 4, wherein one end of each of said contact springs is fastened to an insulating strip (603, 604) and the other end is biased towards the movable contact springs of said printed circuit, said biased ends of the fixed contact springs being supported by a free part of one of said insulating strips (603,604) which serves as a fastening means for fixed contact springs belonging to the next row or column.
 6. A device according to claim 3, wherein each movable contact spring is provided with a number of lugs (801, 802), said lugs penetrating holes in said printed circuit board and cooperating with electric conducting layers (710 a) located on the other side of said printed circuit board.
 7. A device according to claim 6, wherein said additional conducting layer (710a) for one contact spring has the shape of an ''''L'''' the one part of which extends in parallel to the contact spring and the other part of which extends at a right angle to said contact spring, said last mentioned part extending all the way to the edge of the card where it forms a contact surface for the contact spring.
 8. A device according to claim 3, wherein the printed circuit board is provided with a number of openings (610'' - 615'') located adjacent to the contact surfaces of the movable contact springs, and in which pins or ribs or other actuating members penetrate said openings for transmitting movement from the armatures located at one side of the board to the springs located at the other side of the board.
 9. A device according to claim 5, in which each insulating strip is provided with grooves in which electrically conducting layers are located and in which the contact springs are located at the other side of said strip and holes are provided through the insulating strips through which said conducting layers penetrate and make contact with the fixed contact springs.
 10. In an electromagnetic device with a group of relays, for example in a coordinate selector where the relays are arranged in lines and columns crossing each other, each relay including a magnetic circuit, each magnetic circuit comprising a stationary part and a movable armature of magnetically conducting material, a pivot where a first part of said armature is pivoted to a first portion of the stationary part; a working airgap between a second part of the armature and a second portion of the stationary part, at least one extra airgap between a third part of the armature and a third portion of said stationary part; each said circuit further comprising a first magnetically conducting path adapted to close itself over said working airgap and a second magnetically conducting path adapted to close itself over said extra airgap, both of said magnetically conducting paths passing a common portion of said armature, there being further a working winding which is common for both of said magnetically conducting paths and an extra winding which is provided for the second magnetically conducting path, and wherein said working winding surrounds said common portion of the armature and said extra winding surrounds a portion of said stationary part which is included solely in said second magnetically conducting path; a first plate of magnetizable material comprises said second portion of the stationary part for the magnetic circuits of a plurality of the relays; a second plate comprises said third portion of the stationary part of the same magnetic circuits for said plurality of relays; said plates each having a portion which is substantially parallel to a corresponding portion of the other plate; said two plates being in magnetical connection with each other along at least one of their edges; and wherein for each magnetic circuit sAid armature and the working winding is provided in an opening in said first plate, the armature being pivoted near to one of the boundary borders of said opening and the working airgap being provided near to the opposite boundary border of said opening.
 11. A device according to claim 10, wherein for the armatures of a plurality of the magnetic circuits which are located side by side in parallel to each other a common working winding which surrounds all these armatures is provided, said working winding being located in one single opening provided for all of said armatures in said first plate (110).
 12. A device according to any of the claims 10, wherein the working winding for each armature is provided in a coil bobbin, said coil bobbin being kept in place in a associated opening in said first plate (110) by means of lugs provided on said bobbin, said lugs having for example barb-like projections which grasp the edges of the opening and wherein said armature is kept in the opening of the bobbin by means of a leaf spring which also serves to keep the non-pivoted end of the armature against the end of the associated pin (210,220,230) when the armature is in its non actuated position.
 13. In an electromagnetic device with a group of relays, for example in a coordinate selector where the relays are arranged in lines and columns crossing each other, each relay including a magnetic circuit, each magnetic circuit comprising a stationary part and a movable armature of magnetically conducting material, a pivot where a first part of said armature is pivoted to a first portion of the stationery part, a working airgap between a second part of the armature and a second portion of the stationary part, at least one extra airgap between a third part of the armature and a third portion of said stationary part; each said circuit further comprising a first magnetically conducting path adapted to close itself over said working airgap and a second magnetically conducting path adapted to close itself over said extra airgap, both of said magnetically conducting paths passing a common portion of said armature, there being further a working winding which is common for both of said magnetically conducting paths and an extra winding which is provided for the second magnetically conducting path, and wherein said working winding surrounds said common portion of the armature and said extra winding surrounds a portion of said stationary part which is included solely in said second magnetically conducting path; a first plate of magnetizable material comprises said second portion of the stationary part for the magnetic circuits of a plurality of the relays; a second plate comprises said third portion of the stationary part of the same magnetic circuits for said plurality of relays; said plates each having a portion which is substantially parallel to a corresponding portion of the other plate; said two plates being in magnetical connection which each other along at least one of their edges; and wherein each plate has the shape of an elongated rib, which is common for a plurality of armatures arranged side by side, which armatures are surrounded by a coil which may be common for all the armatures, and that a surface is provided at one edge of said plates which surface forms a pole piece for the working airgaps for all the armatures and that said second plate has pins directed against the armatures and extending from the edge of the other plate, said pins forming pole pieces in the extra airgap, said plates being magnetically connected to each other along the edges which are opposite to the edges provided with pole pieces.
 14. A device according to claim 13, wherein a plurality of units comprising said two plates with associated armatures and windings are assembled together in parallel to each other to form a coordinate selector.
 15. In an electromagnetic device, a number of magnetic circuits, each circuit comprising a stationary part and a movable armature of magnetically conducting material, a pivot where a first part of said armature is pivoted to a first portion of the stationary part, a working airgap between a second part of the armature and a second portion of the stationary part, at least one extra airgap between a third part of the armature and a third portion of said stationary part; each said circuit further comprising a first magnetically conducting path adapted to close itself over said working airgap and a second magnetically conducting path adapted to close itself over said extra airgap, both of said magnetically conducting paths passing a common portion of said armature, there being further a working winding which is common for both of said magnetically conducting paths and an extra winding which is provided for the second magnetically conducting path, and wherein said working winding surrounds said common portion of the armature and said extra winding surrounds a portion of said stationary part which is included solely in said second magnetically conducting path, means for supplying magnetizing current to said working winding, and means for supply magnetizing current to said extra winding.
 16. A device according to claim 15 in which each magnetic circuit is comprised in a relay of a group of relays, for example in a coordinate selector, where the relays are arranged in lines and columns crossing each other, wherein a first plate (110) of magentizable material comprises said second portion of the stationary part for the magnetic circuits of a plurality of the relays, and a second plate (211) comprises said third portion of the stationary part of the same magnetic circuits, said plates having each a portion which is substantially parallel to a corresponding portion of the other plate, said two plates being in magnetical connection with each other along at least one of their edges.
 17. In an electromagnetic device, a number of magnetic circuits, each circuit comprising a stationary part and a movable armature of magnetically conducting material, a pivot where a first part of said armature is pivoted to a first portion of the stationary part, a working airgap between a second part of the armature and a second portion of the stationary part, at least one extra airgap between a third part of the armature and a third portion of said stationary part; each said circuit further comprising a first magnetically conducting path adapted to close itself over said working airgap and a second magnetically conducting path adapted to close itself over said extra airgap, both of said magnetically conducting paths passing a common portion of said armature, there being further a working winding which is common for both of said magnetically conducting paths and an extra winding which is provided for the second magnetically conducting path, and wherein said working winding surrounds said common portion of the armature and said extra winding surrounds a portion of said stationary part which is included solely in said second magnetically conducting path, said extra winding being located adjacent to said extra airgap.
 18. In an electromagnetic device, a number of magnetic circuits, each circuit comprising a stationary part and a movable armature of magnetically conducting material, a pivot where a first part of said armature is pivoted to a first portion of the stationary part, a working airgap between a second part of the armature and a second portion of the stationary part, at least one extra airgap between a third part of the armature and a third portion of said stationary part; each said circuit further comprising a first magnetically conducting path adapted to close itself over said working airgap and a second magnetically conducting path adapted to close itself over said extra airgap, both of said magnetically conducting paths passing a common portion of said armature, there being further a working winding which is common for both of said magnetically conducting paths and an extra winding which is provided for the second magnetically conducting path, and wherein said working windIng surrounds said common portion of the armature and said extra winding surrounds a portion of said stationary part which is included solely in said second magnetically conducting path, said extra winding being located adjacent to said extra airgap, means for supplying magnetizing current to said working winding, and means for supplying magnetizing current to said extra winding. 